fix: bound task failures and release stalled workers

tests/unit/tools/test_utils.py

@@ -47,6 +47,17 @@ else:
     del sys.modules["artemis.graph.state"]
 
 
+import base64
+from io import BytesIO
+from PIL import Image
+
+
+def _valid_screen_base64():
+    buffer = BytesIO()
+    Image.new("RGB", (64, 64), "white").save(buffer, format="PNG")
+    return base64.b64encode(buffer.getvalue()).decode("ascii")
+
+
 @pytest.fixture
 def mock_context():
     """Create a mock ArtemisContext for testing."""
@@ -70,6 +81,7 @@ def mock_context():
 
     # Mock the ADB client for Android
     mock_response = Mock()
+    mock_response.base64 = _valid_screen_base64()
     mock_response.json.return_value = {"elements": []}
     ctx.ui_adb_client.get_screen_data = Mock(return_value=mock_response)
     ctx.ui_adb_client.get_hierarchy = Mock(
@@ -288,6 +300,7 @@ class TestFocusElementIfNeeded:
         focused_element["attributes"]["focused"] = "true"
 
         mock_response = Mock()
+        mock_response.base64 = _valid_screen_base64()
         mock_response.json.return_value = {"elements": [focused_element]}
         mock_context.ui_adb_client.get_screen_data = Mock(return_value=mock_response)
         mock_find_element.return_value = focused_element["attributes"]
@@ -366,6 +379,7 @@ class TestFocusElementIfNeeded:
         }
 
         mock_response = Mock()
+        mock_response.base64 = _valid_screen_base64()
         mock_response.json.return_value = {"elements": [element_from_text]}
         mock_context.ui_adb_client.get_screen_data = Mock(return_value=mock_response)
         mock_find_id.return_value = element_from_id
@@ -401,6 +415,7 @@ class TestFocusElementIfNeeded:
         }
 
         mock_response = Mock()
+        mock_response.base64 = _valid_screen_base64()
         mock_response.json.return_value = {"elements": [element_with_bounds]}
         mock_context.ui_adb_client.get_screen_data = Mock(return_value=mock_response)
         mock_find_text.return_value = element_with_bounds["attributes"]
@@ -428,6 +443,7 @@ class TestFocusElementIfNeeded:
         """Test failure when no locator can find an element."""
 
         mock_response = Mock()
+        mock_response.base64 = _valid_screen_base64()
         mock_response.json.return_value = {"elements": []}
         mock_context.ui_adb_client.get_screen_data = Mock(return_value=mock_response)
         with (